For statement

Simple loop

for initializer[, end] {
    // statements
}

for i = 1, 10 {
    puts i
}

The variable i be declared implicitly, and belong to the loop scope.

for i = 0, 20 {
    if i % 2 == 0 {
        puts i
    }
}

for i = 20, 1 {
    puts i
}

But no parenthese, comma instead of semicolon.

for [initializer], condition, [updater] {

}

for i = 0, i < 5, i++ {
    // do something
}

var i = 0    // now the initializer here
for , i < 5, i++ {
    // do something
}

for i = 0, i < 5, {
    i++ // own updater
}

If the last comma is removed, the loop becomes Simple loop.

Iterating through an array, map.

for <first> [, <second>] : <expr> <body>

With an array:

var arr = [1, 2, 3]
for v, i : arr {
    puts v, i    // value - index
}

Just use for v : arr to get the value only.

for v : arr {
    puts v
}

With a map:

var map = { a: 4, b: 5, c: 6 }
for k, v : map {
    puts k, v    // key - value
}

Depend on the implementation, the key - value pairs may not in input order.

So the output of above example could be:

a   4
b   5
c   6

... or

b   5
c   6
a   4

Like array, just get the key only:

for k : map {
    puts k
}

Just use for without any option.

for {
    // do something
}

for i = 1 {
    puts i++
}

Consider before using the infinite loop, that will make your program gets stuck.

Last updated 4 years ago

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